1. Field of the Invention
This invention relates to a connector including an attachment plug and a jack, and particularly relates to an improvement of such a connector for use in a wiring cable for connecting a mobile antenna and a transmitter-receiver with each other.
2. Background
FIGS. 3 and 4 show an example of a conventional technique disclosed in Japanese Utility Model No. Hei. 2-11743. The illustrated connector A is used in a wiring cable for connecting a mobile antenna and a transmitter-receiver. The connector A includes an attachment plug Al and a jack A2.
The attachment plug Al has a plug body b with an attachment pin A planted in its forward end. A spring piece c is mounted in the plug body b. The spring piece c can press against the inner circumferential surface of a hollow cylindrical socket t of the jack A2. Lock portions d and lock release portions e are projecting from an outer circumferential surface b1 of the plug body b. The lock portions d are sinkable but can return to their initial positions automatically by their own elastic force after they are sunk. The lock release portions e are also sinkable but can return to their initial positions automatically by their own elastic force. Furthermore, the lock release portions e are designated so as to compel the lock portions d to sink.
The jack A2 has the hollow cylindrical socket f into which the plug body b of the attachment plug A1 is to be inserted. The socket f has an outer cylinder f1 and a metal sleeve f2 closely contacting with the inner circumferential surface of the outer cylinder f1. An engagement portion h is formed on the socket f all over its inner circumference at a plug insertion inlet g through which the attachment plug A1 is to be inserted, so that the engagement portion h locks the lock portions d of the attachment plug A1 in the socket f through elastic displacement of the lock portions d when the attachment plug A1 is attached into the Jack A2.
In FIGS. 3 and 4, the reference symbol m designates a wiring cable attached to the attachment plug A1, and n designates a wiring cable attached to the jack A2.
In the connector A, an inner circumferential surface i of the engagement portion h of the socket f of the jack A2 is a slope so that the inner diameter of the engagement portion h is reduced gradually from a deeper portion of the socket f to the plug insertion inlet g. As is clearly shown in FIG. 4, after the attachment plug A1 has been attached into the jack A2, the top ends of the sinkable lock portions d of the attachment plug A1 abut against the inner circumferential surface i which is a slope, and the lock portions d of the attachment plug A1 is locked by the engagement portion h of the socket f of the jack A2.
However, in the connector A, when at least one of the attachment plug A1 and the jack A2 is pulled after the attachment plug A1 has been attached into the jack A2, lock reaction force acts on the sinkable lock portions d of the attachment plug A1 in the direction to cause elastic displacement of the lock portions d. Therefore, there is a possibility such that the lock portions d are sunk gradually along the inner circumferential surface i of the engagement portion h of the jack A2.
Accordingly, in the conventional connector A, there was a problem that even if the attachment plug A1 and the jack A2 were connected firmly, the connection between the attachment plug A1 and the jack A2 might be released when at least one of the attachment plug A1 and the jack A2 was pulled.